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Outline and Goals l Define what is (and isn’t) a grid in terms of a layered protocol architecture l Understand the role of protocols, services, APIs and tools in the deployment and use of Grids l Understand what role Globus plays l Understand the role of other technologies

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What is a Grid? l Grid language has been driven by genesis from metacomputing, but… l In practice, the Grid is about resource sharing and coordinated problem solving in dynamic, multi-institutional virtual organizations l Focus on how to enable, maintain and control the sharing of resources to achieve a common goal

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Some Useful Definitions l Network Protocol u A formal description of message formats and a set of rules for exchange of messages u Rules define sequences of message exchange, and potentially resulting behavior l Protocol may define state-change in endpoint l Network Enabled Services u Defines a set of capabilities u Protocol defines interaction with service l All services require protocols, although not all protocols are to services

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More definitions l Resource u Entity that is to be shared u Provides some capabilities, that can be accessed via interface (API) or protocol l Application Programmer Interface (API) l Software Development Kit (SDK) u Package that enables application development, consisting of one or more APIs, and programming tools

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Important Points l Being Grid-enabled requires speaking appropriate protocols u Protocol only requirement, not reachability u Protocols can be used to bridge local resources or “local Grids” l Intergrid as analog to Internet l Built on Internet protocols l Independent of language and implementation u Focus on interaction over network l Services exist at each level

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User Protocols l In general, there are many of these, they tend to be on off, and not well defined l Examples: u Portal toolkits (e.g. Hotpage) u Netsolve u Cactus framework

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Summary l Grids are about sharing, not making big MPI jobs l Well defined protocol architecture is essential to understanding and progress u Provides a framework for figuring out where the pieces fit l Globus provides many basic protocols and services u Interoperability between different Grid components